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排序方式: 共有693条查询结果,搜索用时 31 毫秒
51.
Some tetracycline (TC) antibiotics, including TC and anhydrotetracycline, have been found to enhance specific binding of low
density lipoprotein (LDL) to both LDL receptor-positive and-negative cells at relatively higher concentrations. When incubated
at 37°C, the ability of LDL receptor-negative human fibroblasts to bind 125I-LDL was increased from<2 to 45 ng/mg by 170 μM TC. In normal human fibroblasts and Hep G2 cells, 125I-LDL binding was elevated 1.4- to 2-fold by 113 μM TC. The 125I-LDL binding in the presence of TC was diminished by both heparin and EDTA. The enhancement by TC was not observed when 125I-LDL binding was assayed at 4°C. TC enhanced LDL binding to paraformaldehyde-fixed Hep G2 cells, excluding LDL receptor induction
in the mechanism. These results demonstrated that TC enhanced cellular LDL binding through a process not involving functional
LDL receptors. 相似文献
52.
53.
Takeshi Takahashi Kyosuke Kojima Wei Zhang Kanae Sasaki Masaru Ito Hironori Suzuki Masato Kawasaki Soichi Wakatsuki Terunao Takahara Hideki Shibata Masatoshi Maki 《International journal of molecular sciences》2015,16(2):3677-3699
ALG-2, a 22-kDa penta-EF-hand protein, is involved in cell death, signal transduction, membrane trafficking, etc., by interacting with various proteins in mammalian cells in a Ca2+-dependent manner. Most known ALG-2-interacting proteins contain proline-rich regions in which either PPYPXnYP (type 1 motif) or PXPGF (type 2 motif) is commonly found. Previous X-ray crystal structural analysis of the complex between ALG-2 and an ALIX peptide revealed that the peptide binds to the two hydrophobic pockets. In the present study, we resolved the crystal structure of the complex between ALG-2 and a peptide of Sec31A (outer shell component of coat complex II, COPII; containing the type 2 motif) and found that the peptide binds to the third hydrophobic pocket (Pocket 3). While amino acid substitution of Phe85, a Pocket 3 residue, with Ala abrogated the interaction with Sec31A, it did not affect the interaction with ALIX. On the other hand, amino acid substitution of Tyr180, a Pocket 1 residue, with Ala caused loss of binding to ALIX, but maintained binding to Sec31A. We conclude that ALG-2 recognizes two types of motifs at different hydrophobic surfaces. Furthermore, based on the results of serial mutational analysis of the ALG-2-binding sites in Sec31A, the type 2 motif was newly defined. 相似文献
54.
H. Hasegawa M. Azizur Rahman K. Kitahara Y. Itaya T. Maki K. Ueda 《The Science of the total environment》2010,408(7):1684-1690
In this study, the influence of eutrophication on arsenic speciation in lake waters was investigated. Surface water samples (n = 1-10) were collected from 18 lakes in Japan during July 2007 and February 2008. The lakes were classified into mesotrophic (7 lakes) and eutrophic (11 lakes) based on the total phosphate (T-P) and chlorophyll-a (Chl-a) concentrations in water column. Inorganic, methylated and ultraviolet-labile fractions of arsenic species were determined by combining hydride generation atomic absorption spectrometry with ultraviolet irradiation. Organoarsenicals (mainly methylated and ultraviolet-labile fractions) comprised 30-60% of the total arsenic in most lakes during summer. On the other hand, inorganic arsenic species (As(III + V)) dominates (about 60-85%) during winter. The occurrence of ultraviolet-labile fractions of arsenic was higher in eutrophic lakes than those in mesotrophic lakes in both seasons. The concentration of dimethyl arsenic (DMAA) was high in eutrophic lakes during winter; and in mesotrophic lakes during summer. The results suggest that the conversion of As(III + V) to more complicated organoarsenicals occurred frequently in eutrophic lakes compared to that in mesotrophic lakes, which is thought to be the influence of biological activity in the water column. The distribution of arsenic species were well correlated with phosphate concentrations than those of Chl-a. This might be due to the competitive uptake of As(V) and phosphate by phytoplankton. The organoarsenicals (OrgAs)/As(V) ratio was higher at low phosphate concentration indicating that conversion of As(V) to OrgAs species was more active in phosphate-exhausted lakes with high phytoplankton density. 相似文献
55.
For the construction of a microwave-assisted organic synthesis plant, it is necessary to know the dielectric properties of the reaction system. Measurements of the dielectric properties of lactic acid aqueous solution, anhydrated lactic acid, oligo(lactic acid) and water, which are constituent materials in the polycondensation of lactic acid, confirm that dielectric properties decrease as reaction progresses. Calculated microwave penetration depths, obtained from the dielectric properties, show that microwaves penetrate deeply into the reaction system. This work should be useful for the development of microwave-assisted organic syntheses in the chemical industry. 相似文献
56.
Daisuke Kosemura Maki Hattori Tetsuya Yoshida Toshikazu Mizukoshi Atsushi Ogura 《Journal of Electronic Materials》2010,39(6):694-699
Defects and stress gradually accumulate throughout various Si large-scale integration fabrication processes. It is essential
to monitor defects and stress carefully to suppress their unintentional introduction. In this study, we measured the stress
and crystal quality in shallow trench isolation (STI) samples by ultraviolet (UV)-Raman spectroscopy with an extremely high-resolution
wavenumber to evaluate the effect of post-annealing on the recovery of Si crystals. The variations of crystal quality in 200-mm
wafers with STI structures gradually decreased after post-annealing for 4 h, 6 h, and 8 h; however, there was no substantial
difference in the values of full-width at half-maximum of the Raman spectra. Precise measurements of variations of stress
and crystal quality were successfully performed by UV-Raman spectroscopy with a high-resolution wavenumber, which enabled
us to evaluate the STI process accurately. 相似文献
57.
Nakano M Furukawa M Tsuji S Tonogai Y 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(5):283-288
Japan's Specifications and Standards for Food Additives, 7th Edition (JSFA-VII) does not set limits for total contents of water-soluble chlorides and water-soluble sulfates (water-soluble inorganic salts) in food color aluminum lakes (FC-Als). However, the regulatory limit is 2% in JECFA and CFR. We used column switching suppressor-type ion chromatography (CSS-IC) for determination of anions. The total contents of water-soluble inorganic salts in FC-Als (112 qualified samples) were determined using the modified CSS-IC from fiscal year 1998 to fiscal year 2003. Total contents of water-soluble inorganic salts in four samples exceeded 2%. From an international point of view, it is desirable that the total content of water-soluble inorganic salts in FC-Al should again be regulated in Japan. 相似文献
58.
N. Mahmed O. Heczko R. Maki O. Söderberg E. Haimi S-P. Hannula 《Journal of the European Ceramic Society》2012,32(11):2981-2988
The properties of the bulk materials consolidated of silica coreshell powders with iron oxide core have been studied. Iron oxide nanoparticles smaller than 20 nm in size were synthesized by a reverse co-precipitation process in ambient atmosphere. Coreshell structures with various amounts of iron oxide were prepared via a modified Stöber method. The powders were compacted by using pulsed electric current sintering (PECS) at 1373 K. The morphologies, microstructures, phases, optical, and magnetic properties of the samples were studied by using transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), UV–visible spectroscopy (UV–Vis), and vibrating sample magnetometer (VSM). Transmittance values in the 250–800 nm range varied with the amount of iron oxide. Sample with the lower content was transparent while the sample with the highest content was opaque with microporosity. The compact with the highest iron oxide content showed the ferromagnetic behaviour at 300 K. The phase transformations in the coreshell powders during the sintering process are discussed. 相似文献
59.
Sato H. Wada T. Ohbayashi S. Kozaru K. Okamoto Y. Higashide Y. Shimizu T. Maki Y. Morimoto R. Otoi H. Koga T. Honda H. Taniguchi M. Arita Y. Shiomi T. 《Solid-State Circuits, IEEE Journal of》1999,34(11):1571-1579
This paper describes a 0.25-μm, 64 K×36 bit pipelined burst SRAM using a 6.156-μm2 cell. It realizes over 500-MHz operation using a lower cost double metal process, Internal 16 K×144 organization by T-shaped bit line array reduces 20% of latency, 20% of active power, and 8.5% of die size. The low power also enables us to use lower cost thin quad flat type packages. Our solution to the soft error problem, a shallow triple well structure and four-transistor cell with stacked capacitor, improved soft error rate by 3.5 orders of magnitude compared with the conventional SRAM cell 相似文献
60.
Xu D. Suemitsu T. Osaka J. Umeda Y. Yamane Y. Ishii Y. Ishii T. Tamamura T. 《Electron Device Letters, IEEE》1999,20(5):206-208
We have developed high-performance enhancement-mode InP-based modulation-doped field-effect transistors with 0.03 μm gate-length. A record high current gain cutoff frequency exceeding 300 GHz has been achieved, and the maximum extrinsic transconductance is as high as 2 S/mm with an associated drain current of 0.5 A/mm at a drain bias of 1 V. This high performance is a result of the reduction or gate length, the use of the high barrier metal Pt as gate electrodes, and most importantly the employment of the well-developed wet-etching technology that allows the formation of a very deep gate groove while retaining small side etching. The excellent E-MODFET performance opens up the possibility of implementing ever faster high-speed circuits based on direct-coupled FET logic 相似文献